How does a poison make a catalyst inactive?

It is strongly adsorbed on the active sites (or forms a stable compound), so reactants cannot be adsorbed

It lowers the activation energy too much

It increases the surface area of the catalyst

Which poison-catalyst pair is correct?

As2O3 poisons Pt in the contact process

As2O3 promotes Pt in the contact process

H2S promotes Fe in Haber's process

CO promotes Pt in a catalytic converter

2069 Bhadra · 1.5 marks

Catalytic poisoning

Short answer

Catalytic poisoning is the loss of catalyst activity caused by a poison strongly adsorbed on active sites, blocking reactants. Examples include As₂O₃ poisoning Pt in the contact process and H₂S poisoning Fe in Haber's process. It can be temporary or permanent.

Explain the term: Catalytic poisoning.

Catalytic poisoning is the loss of activity of a catalyst caused by a small amount of a foreign substance (the poison). The poison is strongly adsorbed on the active sites of the catalyst and blocks them, so reactants cannot reach the surface.

Examples: As₂O₃ poisons the Pt catalyst in the contact process; H₂S and CO poison the Fe catalyst in Haber's process. Poisoning may be temporary or permanent.

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